Intragastric preloads of l-tryptophan reduce ingestive behavior via oxytocinergic neural mechanisms in male mice

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Sarah N GartnerP K Olszewski

Abstract

Human and laboratory animal studies suggest that dietary supplementation of a free essential amino acid, l-tryptophan (TRP), reduces food intake. It is unclear whether an acute gastric preload of TRP decreases consumption and whether central mechanisms underlie TRP-driven hypophagia. We examined the effect of TRP administered via intragastric gavage on energy- and palatability-induced feeding in mice. We sought to identify central mechanisms through which TRP suppresses appetite. Effects of TRP on consumption of energy-dense and energy-dilute tastants were established in mice stimulated to eat by energy deprivation or palatability. A conditioned taste aversion (CTA) paradigm was used to assess whether hypophagia is unrelated to sickness. c-Fos immunohistochemistry was employed to detect TRP-induced activation of feeding-related brain sites and of oxytocin (OT) neurons, a crucial component of satiety circuits. Also, expression of OT mRNA was assessed with real-time PCR. The functional importance of OT in mediating TRP-driven hypophagia was substantiated by showing the ability of OT receptor blockade to abolish TRP-induced decrease in feeding. TRP reduced intake of energy-dense standard chow in deprived animals and energy-dense p...Continue Reading

Citations

Nov 20, 2018·Journal of Neuroendocrinology·Gareth Leng, John A Russell
Apr 5, 2019·Current Nutrition Reports·Pawel K OlszewskiAllen S Levine
Oct 28, 2019·Journal of Neuroendocrinology·Elizabeth A LawsonJames E Blevins
Jun 4, 2019·Frontiers in Endocrinology·Mitchell A HeadPawel K Olszewski
Jan 2, 2022·Molecular Metabolism·Serena BoscainiJohn F Cryan

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